Food preparation systems are well known in the food science and consumer goods area. Such systems allow a consumer to prepare at home a given type of food, for instance a beverage such as a coffee-based beverage, e.g. an espresso or a filter-like coffee cup.
In the following description, the invention will described in relation to a specific application to beverage preparation systems. However, the invention globally encompasses systems for non-beverage items preparation, such as for instance ice cream, soups comprising particles (herbs, croutons, etc.), jellies, dairy items (e.g. yogurts, cream desserts, etc.), or any kind of similar non liquid flowable edible products.
Today, most preparation systems for in-home food and beverage preparation comprise a machine having a so-called “brewing chamber” or “brewing unit” or “extraction chamber” which can accommodate portioned ingredient for the preparation of the food or beverage. A brewing unit comprises several parts which are designed to be assembled so as to create a closed cavity wherein the food or beverage ingredient can be placed. The brewing unit comprises means for injecting a preparation medium under pressure such as a fluid which is typically water through the ingredient, so as to prepare a corresponding food or beverage, which is then dispensed out of the brewing unit to the consumer. The preparation fluid is sourced from a fluid conducting system of the machine to which the brewing unit is connected. The preparation is performed within the brewing unit at a pressure above the atmospheric pressure, which is typically comprised between 1 and 20 bar, preferably between 2 and 15 bar (relative pressure).
The preparation is performed by passing preparation fluid through the ingredient contained in a capsule or pod. For this reason, it is an essential characteristic of a brewing unit to be able to withstand a pressure difference between inside the cavity, and the ambient pressure (which is generally equal or substantially equivalent to atmospheric pressure) without opening itself when pressure inside the cavity increases (typically fluid pressure, e.g. water pressure).
Ingredient portions are pre-dosed before they are placed into the cavity of the brewing unit, and can take the form of soft pods or pads, or sachets. More and more systems utilize semi-rigid or rigid portions such as rigid pods or capsules. In the following, it will be considered that the beverage machine of the invention is a beverage preparation machine working with a rigid or semi-rigid capsule, to be placed directly into the brewing unit of the machine.
As said above, the so-called “brewing unit” of a machine comprises a receptacle or cavity for accommodating the ingredient capsule, and a fluid injection system for injecting a fluid, preferably water, under pressure through said ingredient, preferably by piercing through a wall of the capsule that contains the ingredient (in some instances though, if the ingredient capsule is open along at least one its sides, it is not necessarily mandatory to pierce the capsule walls to inject an extraction fluid therein. Fluid injection means can typically comprise at least one needle, able to pierce the capsule walls if needed. Water injected under pressure through the ingredient, for the preparation of a coffee beverage according to the present invention, is preferably hot, that is to say at a temperature above 70° C. However, in some particular instances, it might also be at ambient temperature, or even chilled. The pressure inside the brewing unit during extraction and/or dissolution of the ingredient is typically about 1 to about 8 bar for dissolution products and about 2 to about 12 bar for extraction of roast and ground coffee.
Some food and beverage preparation systems have been developed, wherein the brewing unit can be detached from the main machine body so that the machine is modular: it gives the possibility to the consumer to adapt one or another brewing unit corresponding to a particular type of ingredient capsule, according to its needs. Some capsule types can be larger or taller, or have different shapes depending on the type of beverage ingredient contained therein. In this case, it is possible to detach the brewing unit from the beverage machine base, so that said brewing unit is easier to clean (the brewing unit is usually the functional part of the machine which is in contact with the ingredient or the beverage, and therefore it more likely to need regular maintenance and cleaning). The main machine base contains all functional elements necessary for circulating and preparing the brewing fluid for injection into the capsule or pod ingredient contained in the brewing unit. Such functional elements are selected within the list of, but are not limited to: a fluid source (reservoir or connection to an external fluid source such as tap water for instance), a fluid pump, a fluid heating and/or chilling element, a fluid pipe system to link other functional elements of the beverage machine, a valve system to circulate the fluid from the functional elements of the machine and towards the brewing unit, and a control panel linked to an electronic board for managing the beverage preparation parameters and proper actuation of the functional elements.
Most preferably, such detachable brewing unit must be able to withstand a pressure inside the brewing unit cavity that is above ambient pressure, and can be up to 20 bar, when said brewing unit is functionally attached to the beverage machine base, but also when said brewing unit is detached from the machine base. In other words, opening of the brewing unit must be performed only by the user. Unexpected opening of the brewing unit which is detached from the main machine base must be avoided for safety and cleanliness reasons: such unexpected opening of the brewing unit when internal pressure builds-up could cause splashes of hot food product contained therein, which could cause injuries to the consumer, or at least be messy and therefore undesirable.
In order to facilitate handling of the brewing unit, the cavity is typically made of two parts—a capsule or pod receiving cavity and a closing lid—. Furthermore, in order to ensure that the functional adaptation of both parts is optimal when said brewing unit is closed and ready for use, and to prevent leakage risks, both parts are mechanically mounted one to the other around a pivoting hinge. This guarantees that the brewing unit parts are able to open or close for insertion of an ingredient capsule and withdrawal of the used capsule for disposal, while keeping the attachment between the two as solid as possible when the brewing unit is closed. The two parts of the brewing unit can be locked in a closed position by actuating manually a locking mechanism, for instance a bayonet system. Such a detachable brewing unit with locking means is described for instance in Applicant's European applications EP AN 12189878 and EP AN 12189875.
It was surprisingly found though, that in some cases, it is very difficult to close the brewing unit when the ingredient capsule or pod inserted therein is too bulky: once inserted in the capsule or pod-receiving part of the brewing unit, said ingredient capsule or pod protrudes therefrom, such that the closing lid part cannot be pivoted properly to close the brewing unit in a functional configuration. This is more particularly problematic because the injection needle is usually attached to the inside of the closing lid and protrudes from the internal surface of said lid in order to pierce the capsule wall at the time the brewing unit is closed. In that case, due to the pivoting movement of the lid part around the hinge, the applicant has found that the needle tears the capsule or pod wall due to the circular movement of the lid part relative to the cavity part, instead of piercing the capsule wall neatly. Tearing of the capsule wall instead of a neat piercing is highly undesirable, as it causes leaks when liquid (usually water) is injected through the needle under pressure. Such leaks can then spill out of the brewing unit which is a concern from safety and cleanliness perspectives.
There is therefore a need for a flowable food, or beverage preparation machine that comprises at least one detachable brewing unit, that obviates the disadvantages of the known systems.